Without given much preamble, Light looks over the tapes from the TV station and voices the same conclusion as L, that there's a second Kira. With this conclusion validated, they work together to draw out the copycat. It works. The copycat gives a live broadcast reply but it proves a liability to Light when the copycat reveals shinigami information best kept secret. Horrified, L now realizes supernatural forces are involved.
Did You Know?
I wonder, what kind of a person are you, imposter?
I wonder, what kind of a person are you, Kira?
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